A series of glasses composed of xB(2)O(3)-8Al(2)O(3)-(90-x)Na2O-R2O3 (x = 65, 70, 75, 80, 85; R = Dy3+, Tb3+, Sm3+) were prepared through melt-quenching. Structural evolution was induced by varying the glass composition. Increasing the glass network former B2O3 enhanced the luminescence of rare-earth ions, as observed in the emission spectra. The mechanism of the glass structural evolution was investigated by the NMR spectra analysis. The dispersant effect of the glass structure was believed to promote the better distribution of the rare-earth ions in the matrix and reduced the concentration quenching between them. The relationship between the glass structure and its optical properties was established.